Manufacture of pulp articles



Patented May 5, 1931 UNITED STATES PATENT OFFICE MILTON O. SGHUR, OF NEWHAMPSHIRE, ASSIGNOR T6 BROWN COMPANY, OF

BERLIN, NEW HAMPSHIRE, A CORPORATION OF J MANUFACTURE OF PULP ARTICLES.Ro Drawing.

This invention relates to the manufacture of pulp articles, and moreparticularly to those comprisinga multiplicity of plies or webs ofinterfelted fiber which are super- '5 posed in wet condition afterformation on suitable web-forming instrumentalities, such as cylinder orwet machines, then dried, and,

" v if desired, impregnated with suitable waterproofing material, suchas pitch. An exam- 10 ple of pulp articles of this class is so-calledfiber conduit, which is made by winding a wet web ofpulp on a mandreltothe desired wall thickness, then removing the mandrel from the resultingtube, drying the tube, and impregnating the tube with pitch. Suchconduit is serviceable for use in housing underground electric wiringsystems and in piping water or other fluids.

One of the important factors incident to the manufacture ofsuch articlesis the use of a stock or furnish leading to wet multi-ply' productswhich are capable of being dried at a high rate. of speed withoutundergoing splitting between laminations, and in the case 95 of wettubes, which do not go out of round during the drying operation. Anotherim-' portant factor is the use of a stock .or furnish which leads to adry multi-ply product of suflicient porosity to undergo impregnation,

80 as with molten pitch, with uniformity and rapidity.

. In the commercial production of articles such as described, and moreparticularly fiber conduit, it is important to attain the forego- 85 ingdesiderata with comparatively inexpensive raw materials. Heretofore ithas been the practice to use as the stockor furnish the cost of'the rawmaterial.

Application filed February 20, 1930. Serial 1T0. 430,145.

way. When the screenings are used alone in practicallyunbeaten-condition, there is very poor bonding between plies, and thetubes are liable to split during drying. When ground-wood is used alone,although the shrinkage of the tubes on dryingis very low and theirporosity high, they are deficient in strength and, because of the poorcohesion between plies, they are liable to split during drying.

Waste paper stock is much less expensive than virgin ground-wood, sothat were it possible to use waste papers with satisfaction in lieu ofground-wood, a very substantial saving in the cost of raw material wouldensue. In the past, attempts to do this have resulted in failure,because tubes made from furnishes containing waste papers invariablyundergo splitting during the drying operation and are of low strength.Apparently the waste paper stock interferes to such an extent with therealization of bonding between plies that the shrinkage strain duringdrying overcomes such bonding as is'obtained and causes separation ofthe plies. I have discovered that if ground charcoal is used as one ofthe components of the furnish, waste papers may be used in place ofvirgin ground-wood, without danger of splitting durin the dryingoperation, and further that t e dry tubes maybe impregnated with greaterfacility and with a higher pitch to her ratio than were the charcoalomitted. This discovery is highly significant from a commercialstandpoint, as it enables a high reduction in I have further found thatif the screenings or other lon fibered stock is used either entirely orpart y in the form of gel, i. e., hydrated as for the manufacture ofglassine paper or even to a greater extent, a further reduction in costmay be effected, as less screenings and still i more waste papers may beused. At thesame time, a material increase in strength of. tubes isrealized when gel is used,-so that strength need not be sacri ced whenwaste papers are substituted for the virgin ground-wood.

Various furnishes falling within the purview of the presentinventlon maybe used,

the waste papers running to as high as 70% of the total solids of thefurnish, the ground charcoal being present to the extent, of say 5% to15%, and virgin cellulose fiber in beaten condition constituting therest of the solids. The Waste papers employed may include newspapers,magazines, cardboard, and other wastes which contain a large proportionof ground-wood.

A specific furnish which has been found to give eminently satisfactoryresults was made up of the following components:

P c t Screenings (thoroughly beaten) 12 2; Waste papers (well-pulped) 42Ground charcoal 15 P V t Waste papers (well-pulped) ii fib Long-fiberedpulp (well-gelled) 25 Ground charcoal 10 The long-fibered pulp may bescreenings. kraft, or sulphitestock, screenings such as obtained fromsulphite pulp being preferred because of their low cost. such stock ispreferably carried out in a stone-roll beater, with the roll so adjustedthat at the end of, say, ten to fifteen hours, the fibers are thoroughlyfibrillated and in highly gelatinized condition.

The procedure preferably followed in producing the furnish is tocondition each component independently and then to mix the components.Such a procedure is preferable, in that each component is conditionedwith greater facility in the absence of the others.

. For instance, the presence ofthe waste papers in the beater in whichgelatinization of the virgin fiber is effected is objectionable in thatthe waste papers impede gelatinization of the virgin fiber and consumeenergy without undergoing much gelatinization. The virgin fiber alone ishence thoroughly gelled as, say,

a 6% stock suspension, as already described.

. in a beater wherein it is well pulpe The waste papers alone arepreferably initially broken up by the use of a so-called hog, whereuponthe disintegrated massis laced with water to form, say, a 6% stocksuspension.

The ground charcoal is thoroughly mixed with water to produce a 10%suspension. The three suspensions are then delivered in the desiredproportions into a tank wherein they are intimately mixed to produce asuspension of, say, about 6%% solids content. This mixture is diluted tothe usual solids The beating of content, say about 5%, in passing to thecylinder machine or other web-forming mechanism.

For the manufacture of tubes which are not to be impregnated, forinstance tubes which are to serve as cores upon which sheet materialsuch as paper may conveniently be wound into rolls, a furnish containinga larger proportion of long-fibered pulp, such as kraft, may be used toadvantage. All of the 'long-fibered component may be wellbeaten or itmay be partly well-beaten and partly well-gelled, as this leads to tubesof high strength. The fact that the tubes may be lower in porosity isimmaterial in such case, as subsequent impregnation of the tubes is noteffected. A typical furnish for such tubes may comprise the followingcomponents:

Per cent Taste papers (well-pulped) 50 Kraft pulp (well-gelled) 20 Kraftpulp (well-beaten) a 20 Ground charcoal 10 While the furnisheshereinbefore given were described as being specifically applicable totube or conduit manufacture, nevertheless these furnishes or othershaving the general composition of the present invention are advantageousin the manufacture of other multifiber furnishes such as described maybe used to advantage in the manufacture of pressed pulp articles and thelike, where cheapness of furnish, strength of product, and ease ofdrying are desirable. They are, however, of maximum advantage in themanufacture of multi-ply pulp articles to be impregnated withwaterproofing materials of the character of pitch, where comparativelyslight changes in the composition of the stocks heretofore used have inthe past given rise to much spoilage inproduct, particularly when dryingand impregnating equipment were operated at normal capacities.

This application is a continuation in art of my application Ser. No.382,202, ed July ,30, 1929, wherein I have disclosed, among otherthings, a furnish for the manufacture of pulp articles containing wastepaper stock and charcoal. I do not herein claim broadly the use ofcharcoal in cellulose pulp furnishes intended for' manufacture intoarticles, and more particularly into multi-ply articles to beimpregnated with media such as asphalt, as'this broader base ofinvention is claimed in application erial No. 382,202. On the contrary,allthe claims herein. presented-involve the use of waste paper stock asan essential ingredient of the pulp furnish or the articlemadetherefrom.

I claim 1. A furnish for the manufacture of pulp articles, comprising anaqueous suspension of a mixture of waste paper stock, ground charcoaland beaten, long-fibered stock.

2. A furnish for the manufacture of pulp articles, comprising an aqueoussuspension of a mixture of waste paper stock, ground charcoal, andhighly gelatinized, virgin,

I long-fibered pulp.

3. A furnish for the manufacture of pulp articles, com risin an aqueoussuspension of a mixture soli s comprising up to about 70% waste paperstock, about to ground charcoal, and virgin cellulose fiber in beatencondition. M

4. A furnish for the manufacture of pulp articles, comprising an aqueoussuspension of a mixture of solids vcomprising the followsignature.

trons given:

Percent i Waste apers in well-pulped condition Long-fi ered pulp inwell-gelled condition I I 25 Ground charcoal 10 5. A process whichcomprises beating virgin cellulose pulp in water to efi'ect itsgelatinization, pulping waste papers in water, forming an aqueoussuspenslon of ground charcoal, and then intimately mim'n all thesematerials to produce a furnish for orming into pulp articles.

6. A pulp article formed of bonded-together webs of interfelted fiberthroughout which ground charcoal is distributed, the fibers comprisingboth waste paper'fiber and beaten virgin fiber.

7., A pitch-impregnated tube made up of I bonded-together convolutionscom rising waste papers, ground charcoal, and aten,

virgin, cellulose fiber.

8. A furnish for the manufacture of pulp articles, comprising an aqueoussuspension of a mixture of waste paper stock, ground charcoal, andcellulose pulp beaten or hydrated to a slimy consistency.

In testimony whereof I have afiixed my MILTON O. SCHUR.

ing components in substantially the propor-

